Spark plug



Jul zo', 1943. 1A. DELIA- 2,324,616

' SPARK PLUG Filed Nov 13, 1941 This invention relates to new and usefulim provementsin sparkplugs for use as ignition means in internal combustion engines.

The objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing wherein satisfactory embodiments of the invention are shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawing:

Fig. 1 is an enlarged elevational view, with parts broken away, of my improved spark plug;

Fig. 2 is a further enlarged view in central section of the inner endportion of the spark plug of the invention;

Fig. 3 is a sectional view on the scale of Fig. 1 of the inner end portion of a spark plug but showing amodification; and I v Fig. 41s a view similar to Fig. 3 but showing a further slight modification.

Referring in detail to the drawing and at first more particularly to Figs. 1 and 2 the spark plug of the invention as shown comprises an outer metalshell H in which ismounted the usual porcelain or other insulator l2. .Shell H is but part of the general assembly Ill and is provided with a portion having flat faces I3 for engagement by a wrench for the applying or removing of the plug to and from an engine block as is usual in the art. At its inner end shell II includes a threaded skirt portion. M for screwing into the usual port provided for that purpose in engine blocks.

The inner end portion I5 of the insulator [2 may be somewhat tapered as shown and may stop slightly short of the inner end of skirt portion l4 although this is a detail with which the present invention is not particularly concerned. Ektending through insulator i 2 is a center electrode 16 of the spark plug Ii] and carried by the skirt portion 14 of the outer metal shell I l is the ground electrode generally designated l1.

According to the presentinvention the inner or free ends of the electrodes 16 and I! are made fiat or straight across as at 19 and i8 respectively. Further the free flat end of one electrode is located in alignment with the adjacent side of the other electrode. Thus in Figs. 1 and 2 the free end I8 of electrode H is in alignment with the near side or the electrode It. To provide the necessary spark-gap the free portion of the eleci-srarts ,PA T

' l r. ".l. Q :srARKPrlnG R l v .rbsefihamilia,Fairnnaoqnir] Application November 13, 1941, Serial No; 418,372 SClainis. joists- 169 trode i1 is inwardly of thefree end of the electrode I6.. r Thus the spark-gap is between the sharp edge or corner 2| of the electrodelB and the similar edge or corner 20 of the electrode I'l. With this described and illustrated construction it is possible to obtain a more instantspark acrossthe gap between 23 and 2| even though the usually required favorable conditions are not present. With flat ended electrodes arranged to provide a spark-gap from the corner of one electrode to a corner of the other a spark may be obtained with weaker current.

When the ends of electrodes are sharpened as to an edge or a point they burn away rapidly and where they are rounded the proper spark is not obtained. Where the sparkgap is from the end of the center electrode to a side portion of the ground electrode the center electrode burns back into a round or convex end and the plug does not function properly. With the described construction illustrated in the present drawing should the immediately adjacent corners burn iii) present corner to corner spark-gap arrangement with the free ends of the electrodes flattened as set forth gives excellent results and with it the functioning of motors on which it has been tried has been'measurably improved. The outer exposed terminal 22 of the center electrode is threaded or otherwise prepared for the reception of a lead as is usual in the art.

Referring now to Fig. 3 in the modification there shown the insulator I5 is illustrated in connection with the inner end of the skirt M of the spark .plug shell. Center electrode 23 has itsinner flat or straight across end 24 in alignment with the side of the ground electrode 25 and the flat free end 26 of the latter is spaced from the center electrode so that the spark-gap between the electrodes is a corner to corner arrangement from the corner or sharp edge 21 of electrode 23 to the corresponding corner or edge portion 28 of the electrode 25. Thus in this modification the spark-gap is the same and for the purpose pointed out when considering Figs. 1 and 2 of thedrawing. a

In the modification of Fig. 4 the shell, insulator and center electrode are constructed as described in connection with the other figures of l the drawing.- That is, center electrode 29 has a fiat inner or free end 30 and the ground electrode 3! of the modification has a flat free end 32 so arranged in relation to the inner end of the center electrode that a spark-gap exists from the corner or sharp edge portion 33 of the center electrode to the near or adjacent sharp corner or edge portion 34 of the electrode 3|. Thus in this construction the spark-gap is arranged as and for the purpose previously described. However, in connection with Fig. 4 attention is called to the fact that the ground electrode 3| is inclined inwardly to drain rapidly if saturated with liquid fuel.

Having thus set forth the nature of my invention, what I claim is:

1. A spark plug having a pair of Wire-like electrodes exposed at its inner end, said electrodes being flat across their said inner ends, said electrodes arranged with a flat end face of one parallel with a side of the other but spaced therefrom whereby the adjacent portions of the electrodes forming a spark-gap comprise a pair of the sharp corner or edge portions of the free ends of the electrodes.

2. A spark plug including a center electrode whereby the adjacent portions of the electrodes forming a spark-gap comprise a pair of sharp corners of the free ends of the electrodes.

3. A spark plug including a center electrode and a ground electrode exposed'at the inner end of the spark plug, said electrodes being flat across their free ends to provide sharp peripherial edges or corners at the free ends of the electrodes, said electrodes arranged with their sharp corners comprising their adjacent portions to form a'sparkgap between sharp 'free edge portions of said flat free ends of the electrodes, and said'g round electrode arranged to incline inwardly of the spark plug to have its free end lowermost whereby to better drain. I I I v JOSEPH A. DELIA. 

